1. Field of the Invention
The invention in general relates to acoustic-optic devices and particularly to acoustic-optic devices with a crystal which imparts higher efficiency to the devices.
2. Description of Related Art
Acoustic-optic devices such as AOTFs (acoustic-optic tunable filters), delay lines, RF spectrum analyzers and laser beam scanners utilize a particular crystal to which is coupled an acoustic transducer. An RF signal applied to the transducer produces an acoustic wave in the crystal which is used to modify light in some manner, projected through the crystal. The term “light” as used herein is meant to apply to radiation of a particular wavelength, not necessarily in the visible portion of the electromagnetic spectrum.
Associated with the crystal is a figure of merit M2 defined by,M2=n6×p2/v2×ρ
Where: n is the refractive index of the crystal; p is the photoelastic coefficient; v is acoustic velocity in the crystal; and ρ is the density of the crystal
Basically, the higher the figure of merit M2, the higher will be the efficiency of the device. For example, in an AOTF, higher efficiency enables higher resolution with lower power requirements. Thus, better and brighter images may be obtained at low power.
The present invention provides for an acoustic-optic device which utilizes a crystal of tellurium, resulting in a figure of merit far greater than current devices.